[PATCH] ASoC: mediatek: mt8188: add constraints for PCM

[Trevor Wu (吳文良)]

On Thu, 2023-06-29 at 16:06 +0100, Mark Brown wrote:
> On Thu, Jun 29, 2023 at 03:59:10PM +0800, Trevor Wu wrote:
> 
> > For certain projects, only a limited number of parameters are
> > necessary.
> > Therefore, it may be beneficial to add constraints that restrict
> > the
> > capacity of the PCM.
> 
> This commit message isn't entirely clear.  The effect of the commit
> is
> to restrict the configurations supported when using a nau8825 but
> it's
> not clear what a nau8825 has to do with this or why we're doing this
> in
> general.  What exactly do you mean when saying that "only a limited
> number of parameters are necessary" and what makes this the case?

Hi Mark,

For instance, some userspace frameworks only support specific sampling
rates such as 48kHz on Chromebook, making other parameters unnecessary.
By restricting the configuration, unexpected usage can be prevented and
the alsa_conformance_test process which checks all parameters provided
by an ALSA driver can be sped up.

Although machine drivers can be reused for multiple projects, not all
projects have the same criterion. Therefore, I will add the criterion
only for mt8188_nau8825 which is used for Chromebook board.
If there are similar criteria for other projects, they can be adopted
in the same way. Perhaps a new constraint, such as DPCM_FE_CONSTRAINT1,
could be introduced for different parameter combinations.

Would it be more beneficial to establish the criteria as a general rule
for this machine driver, while limiting the use of the machine driver
solely to the Chromebook project? Or do you just suggest that I add
more details in the commit messages?

Thanks,
Trevor